It enhances virtually every aspect of Far Cry and pushes the CryEngine further than ever before. It includes new bullet time effect, advanced texturing, sound spatialization, advanced AI scripting, six new weapons, rocket powered proximity mines, and more

The first bit of the movie shows RL proximity mines in slomo then real time. They're an alt fire mode of the RL which shoot proximity mines. They have an audio component to them which attracts the AI. If nothing comes near them for 10 seconds, they detonate anyway. The next bit is a fight in Volcan - you can hear the differences the new sound spacialization scripting makes while firing weapons and bullets whizzing by. The proximity mines being an explosive rather than a rocket makes them effective weapon vs fatboys.

This is 11:47 minutes of gameplay footage preview of the Project X's new bullet time effect which they call "The Cry Effect" that will be coming in the next version of the mod, 4.4. It also shows off some of their new texturing, special effects and gibbing.